TABLE 3.
Age-standardized baseline characteristics by quintile of caffeine intake: Nurses’ Health Study II1
| Caffeine intake quintile |
|||||
| First (n = 18,199) | Second (n = 18,135) | Third (n = 18,106) | Fourth (n = 18,143) | Fifth (n = 18,079) | |
| Caffeine, mg/d | 19 ± 142 | 87 ± 30 | 171 ± 34 | 344 ± 63 | 567 ± 173 |
| Age,3 y | 36 ± 5 | 36 ± 5 | 36 ± 5 | 37 ± 4 | 38 ± 4 |
| BMI (kg/m2), % | |||||
| <20.0 | 14 | 13 | 13 | 12 | 11 |
| 20.0–24.9 | 43 | 41 | 43 | 45 | 44 |
| 25.0–29.9 | 24 | 25 | 24 | 25 | 27 |
| ≥30.0 | 16 | 18 | 17 | 15 | 15 |
| Thiazide use, % | 2 | 2 | 2 | 2 | 2 |
| Calcium supplement use, % | 20 | 18 | 17 | 17 | 16 |
| Calcium, mg/d | 945 ± 435 | 898 ± 403 | 842 ± 374 | 922 ± 383 | 777 ± 364 |
| Potassium, g/d | 2.8 ± 0.9 | 2.8 ± 1.0 | 2.8 ± 0.9 | 3.2 ± 0.9 | 2.9 ± 0.9 |
| Magnesium, mg/d | 311 ± 113 | 306 ± 110 | 301 ± 104 | 335 ± 107 | 306 ± 104 |
| Vitamin C, mg/d | 280 ± 315 | 252 ± 279 | 242 ± 276 | 250 ± 280 | 218 ± 272 |
| Total fructose, g/d | 23 ± 13 | 26 ± 16 | 23 ± 16 | 23 ± 14 | 19 ± 13 |
| Oxalate, mg/d | 122 ± 118 | 130 ± 121 | 137 ± 120 | 147 ± 126 | 128 ± 116 |
| Phytate, mg/d | 784 ± 350 | 774 ± 321 | 757 ± 313 | 831 ± 326 | 730 ± 309 |
| Alcohol intake, g/d | 1.7 ± 4.4 | 2.2 ± 4.9 | 3.1 ± 5.7 | 4.4 ± 7.2 | 4.2 ± 7.0 |
| Fluid intake, L/d | 1.7 ± 0.7 | 1.9 ± 0.7 | 2.0 ± 0.8 | 2.4 ± 0.8 | 2.6 ± 0.9 |
1
Values are standardized to the age distribution of the study population unless otherwise indicated. Values of categorical variables may not sum to 100% because of rounding.
2
Mean ± SD (all such values).
3
Values are not age adjusted.